1. Field of the Invention
The invention relates to a lighting device for streets, pathways and the like, with a lamp unit including a light source and, positioned in front of the light source in the main emission direction, a lens configured to generate a predefined light distribution pattern.
2. Description of Relevant Art
DE 103 30 261 A1 describes a vehicular lighting device which, in addition to a light source and a reflector, is equipped with a lens positioned in front of the light source in the emission direction. The lens is rotationally symmetrical relative to the optical axis of the light source and on the side facing away from the light source it features a total-reflection surface, reflecting the light impinging on it in a direction perpendicular to the main emission and onto a light-exit perimeter. The light is thus deflected sideways toward the reflector surface, with the lens essentially serving as a means for redirecting light toward the lateral reflector surface and not only for generating a predefined light distribution pattern.
EP 1 916 468 A1 describes a lighting device with a lamp unit for streets, pathways and the like, including a light source and, positioned in front of the light source in the main emission direction, a lens serving to generate a predefined light distribution pattern. The lens is dome-shaped and centrically symmetric relative to points on an optical axis of the light source, and features on a light-exit side of the lens facing away from the light source several segmented free-form areas. A light-entrance surface positioned on a light-entrance side facing the light source is spherically shaped. Depending on the curvature of the light-entrance surface of the lens, larger or smaller rectangular light distribution patterns can be generated. However, the lamp units can only serve to illuminate a partial area of a street section that is to be lit. To fully illuminate the entire object street section it is necessary to combine lamp units with variously contoured or shaped lenses.